USB doesn't work when the ATX Raspi is in the mix

[byllc]

The power from the ATX-RaspI +- (right next to the shutdown pins)  is run to a micro usb male header in order to plug in to the female usb header on the Pi and take advantage of the power management on the Pi. So I'm not powering the Pi via GPIO. What happens is that a Raspberry Pi B later model (not a 256mb one from the early batches) will power up and I can use a keyboard, etc.. through it's two USB ports. As soon as I add the ATX raspi to the mix the USB ports stop working.  I'm assuming there is a voltage drop happening somewhere causing the USB ports to not have enough power to function but I'm powering evertything with a 5v, 1a power brick (iphone charger or Asus tablet charger) and it works fine until I wire up the ATXrp.

An interesting secondary happening is I can't seem to get the RPI to power up via gpio headers at all when using the ATXrpi and while this is not really a problem the way I'm using it now, it may indicate something  useful for troubleshooting.

I'm hoping someone here might have seen this before and have some pointers.  Thanks. 

[Felix]

So you're powering the Pi from the USB output into the Pi uUSB jack correct? How long is the cable you're using?
Can you measure the 5V output from the ATXRaspi during boot and after boot?

[byllc]

My ATXRpi didn't come with a USB output header so  I've got a male micro USB header attached to the +- pins right next to the boot and shutdown pins on the ATXRpi.  The Cable I'm using is less than 5 inches.  I'm going to take some measurements tonight and I'll report back.

[Felix]

Can you also take some pictures of how you had it soldered and the connections to your Pi?

[byllc]

Sorry I didn't end up taking pictures because when I moved everything over to a new breadboard to spread things out and get a better photo for you it all worked fine. I moved it back to the same spots in the original bread board and it stopped working again. Either the breadboard is a red herring and I missed something else or I had a bad connection somewhere in the breadboard. Anyways, its all working great now and I've soldered together a board with all the wiring. 

Even though it all seems to work now. While I was testing voltages I was left scratching my head because when I apply the multimeter to the 5V output it is showing 10V. I'm using one of these http://manuals.harborfreight.com/manuals/98000-98999/98025.pdf  on the 200 ACV setting with the hot lead connected to the second port on the device.  If this reading means anything I'll start a second topic.

[Felix]

AC is not = DC
Look for the DC setting.